THE SPINACH FLEA-BEETLE. 



81 



DESCRIPTION. 



The egg. — The egg is subcylindrical, and regularly elliptical in out- 

 line, between two and one-half and three times as long as wide, nar- 

 rowest toward the apex, where it is subtruncate, widest above the mid- 

 dle, base rounded. Color when newly laid, pale orange buff, changing 

 to somewhat brighter orange later. The surface is rather feebly shin- 

 ing and densely covered with minute pits grouped together so as to 

 form, with the clear spaces between the groups, irregular areas, of which 

 the prevailing pattern is imperfect hexagonal. Between 28 and 31 

 appears to be the number of rows of areas in the entire length of the 

 egg. Length, 1.25 to 1.50 mm ; width, 0.40 to 0.57 mm . 



The group of eggs shown enlarged in the figure at b illustrates also 

 the manner of escape of the larva through a hole at one side. The 

 sculpture is shown highly mag- \ 



nified at c. 



Eggs that came under ob- 

 servation were deposited usu- 

 ally in groups of from 4 to 30, 

 and in one case as high as 50, 

 on the ground and on bits of 

 leaves resting on the earth, all 

 the eggs being placed on end 

 closely but loosely together in 

 the same hexagonal order ob- 

 served in the arrangement of 

 the areas of the egg, although 

 naturally this order is less 

 regular. 



The larva. — When first 

 hatched, the larva, as may be 

 seen by comparing the figure 

 at e with c, looks quite unlike 

 the mature form. The tuber- 

 cles which cover the body are somewhat more conspicuous, the head 

 and legs are much larger in proportion, and the spines (see/) protrud- 

 ing from the body are very long, measuring nearly one third that of the 

 body, including the tubercles. The spines are black at the base and 

 nearly white toward their apices, which are capitate, like those of some 

 other species of larvae in the post embryonic stage. The color is nearly 

 uniform light gray, with a slightly pruinose surface, and the head, eyes, 

 sutures of the legs, and certain other portions are darker. The red of 

 some internal portions can be seen through the anterior portion of the 

 body, the thoracic and first abdominal segments. The length, in the 

 somewhat contracted position which the larva assumes in death, is 

 about 1.80 mm ; the width, ().60 mm . 

 13892— No. 19 6 



lb b c 



Fig. 19. — Disonycha xanthomelcena : a, beetle; b, egg 

 mass, showing mode of escape of larva at right; bb, 

 sculpture of egg; c; full grown larva ; d, pupa ; e, newly 

 hatched larva; /, abdominal segment of same— a, c, d, 

 five times natural size; b, e, more enlarged; bb,f, still 

 "more enlarged (original). 



